patch 8.1.1535: popup select test fails on Mac

Problem:    Popup select test fails on Mac.
Solution:   Skip test if clipboard feature not available.
diff --git a/src/version.c b/src/version.c
index 851cd5f..7d4d06d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1535,
+/**/
     1534,
 /**/
     1533,